Changes in Viability, Cell Composition, and Enzyme Levels During Starvation of Continuously Cultured (Ammonia-Limited)
            <i>Selenomonas ruminantium</i>

Mink, Ronald W.; Patterson, John A.; Hespell, Robert B.

doi:10.1128/aem.44.4.913-922.1982

Cited by 24 publications

(9 citation statements)

References 51 publications

(32 reference statements)

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“…While substrate utilization and endproduct formation may not always follow bacterial growth rates (Maeng & Baldwin, 1976a;Tempest, 1978) it does seem likely from the changes in bacterial pool sizes that the growth rate of rumen bacteria did change in the same direction as changes in RNA concentration in bacteria. This would agree with the well established increase in RNA content of bacteria, including rumen bacteria, with increasing growth rate in pure culture (Herbert, 1961;Koch, 1970Koch, , 1980Mink et al 1982). That the ratio of RNA: DNA in rumen bacteria (up to about 14 h after feeding) followed the same pattern as fermentation activity of whole digesta (Fig.…”

Section: Bacterial Pool Size Fermentation Rate and Chemical Compositionsupporting

confidence: 89%

Effects of feeding frequency and level of feed intake on chemical composition of rumen bacteria

John¹

1984

J. Agric. Sci.

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Cell mass (dry matter per cell) and cell composition (concentrations of DNA, RNA, phospholipids, total N, a-dextran, diaminopimelic acid and 18 common amino acids) of rumen bacteria were measured at various times after feeding sheep chaffed lucerne hay (Medicago sativaX,.) once daily. Cell composition was measured with sheep fed once hourly. Total' DNA and RNA pool sizes in the rumen were also measured.While cell composition was not affected by level of feed intake (700 g v. 1050 g dry matter/day), total DNA, RNA and D.M. pool sizes in the rumen increased with increasing feed intake. With sheep on the once daily feeding regimen relative rumen pool sizes in rumen digesta at various times after feeding were: RNA, 4 > 14 > 0 h; DNA, 4 and 14 > 0 h; D.M. 4 > 14 > 0 h. With the hourly feeding regimen pool sizes were similar to the averaged daily values for sheep fed once daily.When sheep were fed once daily bacterial cell mass, DNA and phospholipid concentrations peaked at 12-14 h after feeding and subsequently decreased to the 0 h value. RNA concentration was maximal at about 4 h after feeding and declined to near the 0 h value at about 14 h. RNA concentrations in bacteria were highly correlated with gas production rates by whole rumen digesta. The ratio RNA:DNA was highest shortly after feeding, decreased to below the 0 h value at about 14 h and then increased to the Oh value. The relative concentrations of a-dextran in bacteria were: 4 > 14 > 0 h. Cell composition witli sheep fed hourly tended to reflect the averaged daily values for sheep fed once daily.These results are discussed with regard to changes in estimated fermentation rate and pool size of bacteria in the rumen. It is suggested that changes in average composition (DNA, RNA, total N and RNA: DNA ratio) of mixed rumen bacteria reflect changes in the average growth rate of the population.

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Section: Bacterial Pool Size Fermentation Rate and Chemical Compositionsupporting

confidence: 89%

Effects of feeding frequency and level of feed intake on chemical composition of rumen bacteria

John¹

1984

J. Agric. Sci.

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“…Calculated as ammonia assimilated from GS plus GDH total activities · dilution rate and assuming no other enzymatic mechanisms of ammonia assimilation. The total content of nitrogen-containing material (protein, RNA and DNA) (as % dry wt) has been reported as being lower for ammonia-limited cultures (Mink et al 1982) than for glucose-limited cultures of S. ruminantium (this study). A similar trend was observed in Ent.…”

Section: Viability and Cell Compositionmentioning

confidence: 47%

“…As noted by Russell and Cook (1995), biomass is not directly correlated to ATP expenditure because of cell maintenance, which appears to be more pronounced at low growth rate. Comparison of glucose-(2AE08%, this study) and ammonia-limited culture viabilities (30AE08%, Mink et al 1982) at D of 0AE05 suggests that limitation by energy for slowly growing cells may be more severe than limitation by nitrogen. Previously, Enterobacter aerogenes also exhibited a similar decline in viability as D decreased (Tempest et al 1967), but at low Ds (under both glucose and ammonia limitations), the viability of S. ruminantium cultures appears to be lower than the viability of Ent.…”

Section: Viability and Cell Compositionmentioning

confidence: 69%

Dilution rates influence ammonia-assimilating enzyme activities and cell parameters of Selenomonas ruminantium strain D in continuous (glucose-limited) culture

Patterson

Chalova

Hespell

et al. 2010

Journal of Applied Microbiology

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Aims: The objective of this study was to examine the effect of dilution rates (Ds, varying from 0·05 to 0·42 h−1) in glucose‐limited continuous culture on cell yield, cell composition, fermentation pattern and ammonia assimilation enzymes of Selenomonas ruminantium strain D. Methods and Results: All glucose‐limited continuous culture experiments were conducted under anaerobic conditions. Except for protein, all cell constituents including carbohydrates, RNA and DNA yielded significant cubic responses to Ds with the highest values at Ds of either 0·10 or 0·20 h−1. At Ds higher than 0·2 h−1, fermentation acid pattern shifted primarily from propionate and acetate to lactate production. Succinate also accumulated at the higher Ds (0·30 and 0·42 h−1). Glucose was most efficiently utilized by S. ruminantium D at 0·20 h−1 after which decreases in glucose and ATP yields were observed. Under energy limiting conditions, glutamine synthetase (GS) and glutamate dehydrogenase (GDH) appeared to be the major enzymes involved in nitrogen assimilation suggesting that other potential ammonia incorporating enzymes were of little importance in ammonia assimilation in S. ruminantium D. GS exhibited lower activities than GDH at all Ds, which indicates that the bacterial growth rate is not a primary regulator of their activities. Conclusions: Studied dilution rates influenced cell composition, fermentation pattern and nitrogen assimilation of S. ruminantium strain D grown in glucose‐limited continuous culture. Significance and Impact of the Study: Selenomonas ruminantium D is an ecologically and evolutionary important bacterium in ruminants and is present under most rumen dietary conditions. Characterizing the growth physiology and ammonia assimilation enzymes of S. ruminantium D during glucose limitation at Ds, which simulate the liquid turnover rates in rumen, will provide a better understanding of how this micro‐organism responds to differing growth conditions.

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“…The lack of available substrates results in the formation of smaller cells [5][6][7][8][9][10][11], and a decrease in endogenous respiration [12,13]. To maintain a low endogenous metabolism, resting cells are dependent on protein, RNA, amino acid and/or storage polymer degradation [7,[14][15][16]. Furthermore, it has been shown that both protein and DNA synthesis are necessary for survival during starvation ( [17], Kjelleberg, Conway and StenstrSm, submitted for publication; M~rdrn, Hermansson and Kjelleberg, submitted for publication).…”

Section: Introductionmentioning

confidence: 99%

Relative changes in incorporation rates of leucine and methionine during starvation survival of two bacteria isolated from marine waters

Nyström

Mårdén

Kjelleberg

1986

FEMS Microbiology Letters

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Two copiotrophic Gram‐negative bacteria isolated from marine waters, S14 and Vibrio sp. DW1, were examined for changes in the rate of protein synthesis in the initial phase of energy and nutrient deprivation. The incorporation of [3H] leucine into the trichloroacetic acid (TCA)‐insoluble material was examined as a method for estimating rates of protein synthesis. The incorporation of methionine was measured and compared with the results of leucine incorporation. Protein synthesis was demonstrated throughout a period of 120 h of starvation. The incorporation rate was related to the time of starvation and decreased subsequent to an initial increase during the first few hours of dormancy. Control experiments with proteinase K and chloramphenicol demonstrated that the labelled amino acids were preferentially incorporated into proteins. It was also demonstrated that the uptake of amino acids was not a rate‐limiting step. During the first hours of starvation the ratio of the protein to the dry weight of the S14 cells increased parallel to the increase in the amino acid incorporation rate. The increased activity of the protein‐synthesising system during the first hours of nutrient and energy depletion indicates the presence of an active cellular response to the downshift conditions. Furthermore, these findings are consistent with the increased respiratory activity during the first hours of starvation, which has previously been observed for the bacteria examined in this study.

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Changes in Viability, Cell Composition, and Enzyme Levels During Starvation of Continuously Cultured (Ammonia-Limited) Selenomonas ruminantium

Cited by 24 publications

References 51 publications

Effects of feeding frequency and level of feed intake on chemical composition of rumen bacteria

Effects of feeding frequency and level of feed intake on chemical composition of rumen bacteria

Dilution rates influence ammonia-assimilating enzyme activities and cell parameters of Selenomonas ruminantium strain D in continuous (glucose-limited) culture

Relative changes in incorporation rates of leucine and methionine during starvation survival of two bacteria isolated from marine waters

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